diff --git a/snippets/toPairs.md b/snippets/toPairs.md new file mode 100644 index 000000000..832f81f51 --- /dev/null +++ b/snippets/toPairs.md @@ -0,0 +1,23 @@ +--- +title: toPairs +tags: object,array,intermediate +--- + +Creates an array of key-value pair arrays from an object or other iterable (object, array, string, set etc.). + +Check if `Symbol.iterator` is defined and, if so, use `Array.prototype.entries()` to get an iterator for the given iterable, `Array.from()` to convert the result to an array of key-value pair arrays. +If `Symbol.iterator` is not defined for `obj`, use `Object.entries()` instead. + +```js +const toPairs = obj => + obj[Symbol.iterator] instanceof Function && obj.entries instanceof Function + ? Array.from(obj.entries()) + : Object.entries(obj); +``` + +```js +toPairs({ a: 1, b: 2 }); // [ ['a', 1], ['b', 2] ] +toPairs([2, 4, 8]); // [ [0, 2], [1, 4], [2, 8] ] +toPairs('shy'); // [ ['0', 's'], ['1', 'h'], ['2', 'y'] ] +toPairs(new Set(['a', 'b', 'c', 'a'])); // [ ['a', 'a'], ['b', 'b'], ['c', 'c'] ] +``` diff --git a/test/toPairs.test.js b/test/toPairs.test.js new file mode 100644 index 000000000..f534526f2 --- /dev/null +++ b/test/toPairs.test.js @@ -0,0 +1,17 @@ +const {toPairs} = require('./_30s.js'); + +test('toPairs is a Function', () => { + expect(toPairs).toBeInstanceOf(Function); +}); +test('Creates an array of key-value pair arrays from an object.', () => { + expect(toPairs({ a: 1, b: 2 })).toEqual([['a', 1], ['b', 2]]); +}); +test('Creates an array of key-value pair arrays from an array.', () => { + expect(toPairs([2, 4, 8])).toEqual([[0, 2], [1, 4], [2, 8]]); +}); +test('Creates an array of key-value pair arrays from a string.', () => { + expect(toPairs('shy')).toEqual([['0', 's'], ['1', 'h'], ['2', 'y']]); +}); +test('Creates an array of key-value pair arrays from a set.', () => { + expect(toPairs(new Set(['a', 'b', 'c', 'a']))).toEqual([['a', 'a'], ['b', 'b'], ['c', 'c']]); +});